Unlike their bottom-dwelling counterparts, these fishes hang out near the bottom of the sea floor. This group includes many of the rockfishes and perches.
Density of demersal fishes (MARE data)
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Marine Applied Research and Exploration (MARE) data on abundance of demersal fishes along seafloor transects. Fish are counted using remotely operated vehicle (ROV) visual surveys of mid-depth (20 to 80 meters) rock and subtidal soft bottom in CINMS. Fish density was averaged across all monitoring sites, including sites located inside and outside of marine reserves and conservation areas, to examine course-scale trends. From 2005—2009, fish greater in length than 10 centimeters averaged 110 total fish per kilometer of surveyed transect. In 2014, average total fish per kilometer was 279, an increase of 250 percent. At a finer scale, fish density may be responding differently inside and outside of some marine protected areas (MPAs) in CINMS. Figure: MARE
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Marine Applied Research and Exploration (MARE) data along seafloor transects on abundance of five species of demersal fish, lingcod, sheephead, gopher rockfish, copper rockfish, and vermillion rockfish. Fish density was averaged across all monitoring sites, including sites located inside and outside of marine reserves and conservation areas, to examine course-scale trends. From 2005–2009, the total counts for these five species combined annually averaged 15 total fish per kilometer of surveyed transect. In 2014–2015, average counts per transect rose to 38 and 44 fish, respectively. At a finer scale, fish density may be responding differently inside and outside of some marine protected areas (MPAs) in CINMS. Figure: MARE
Demersal fishes recent trends (NMFS hook & line survey data)
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Box plots for annual size frequency distributions of black abalone Haliotis cracherodii at each island. Blue lines represent mean sizes of H. cracherodii at each island pooled across and sites. Red lines represent the cumulative mean. Figure: Channel Islands National Park
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Location of Southern California Shelf Rockfish Hook and Line Surveys. Annual surveys for reef-associated fish have occurred since 2004 in September and October using 75 hooks per site at depths ranging from 37 to 227 meters. Catch per unit effort (CPUE) per year was calculated for three spatial scales: CINMS included sites within the Channel Islands National Marine Sanctuary boundary (n = 26); CINMS region included sites inside the red box (n = 55); and Southern California Bight included all sites in the sampling program (n = 121). Data source: NMFS NWFSC; Map: M. Cajandig/NOAA
Demersal fishes recent trends (NMFS trawl survey data)
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(left) Mean number of owl limpets Lottia gigantea at each island from 2000–2014. Blue lines represent mean number at each island pooled across fixed plots and error bars were constructed using one standard error from the mean. (right) Box plots for annual size frequency distributions of L. gigantea at each island. Black lines represent mean sizes at each island pooled across fixed plots and sites. Red lines represent the cumulative mean. Figure: Channel Islands National Park
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Locations sampled by the West Coast Groundfish Bottom Trawl Surveys for demersal fish inhabiting trawlable habitat along the upper continental slope and shelf. Annual surveys have occurred along the entire U.S. West Coast from May to October each year at depths from 55 meters to 1,280 meters. Catch per unit effort (CPUE) per year was calculated for three spatial scales relative to Channel Islands National Marine Sanctuary: CINMS included sites within the CINMS boundary (light blue shading, n = 130, 2008–2014, 116 species); CINMS region includes sites inside the red box (n = 639, 2003-–2014, 192 species); Southern California Bight included sites inside the blue box (n = 1,353, 2003–2014, 247 species). Data source: NMFS NWFSC; Map: M. Cajandig/NOAA